A blonde couple was watching a documentary on the TV Channel about an African tribe whose men all had penises 24 inches long. When a male reaches a certain age, a string is tied around his penis and a weight is attached to the other end. After a while, the weight stretches the length of the penis to 24 inches.
Later that evening as the husband was getting out of the shower, his wife looked down at him and said, "What do you say, we try that African string-and-weight procedure?"
Her husband agreed and they tied and string and weight to his penis.
A few days later, the wife asked the husband, "How is our tribal experiment coming along?"
"Well, it looks like we're half-way there," he replied.
"You've grown to 12 inches?!" she said, astonished.
"No... it's turned black," he answered.